In other words, someone does not have to be exclusively homosexual or heterosexual, but can feel varying degrees of both.

Sexual orientation develops across a person's lifetime–different people realize at different points in their lives that they are heterosexual, bisexual or homosexual." Sexual attraction, behavior and identity may also be incongruent, as sexual attraction or behavior may not necessarily be consistent with identity.

Some individuals identify themselves as heterosexual, homosexual or bisexual without having had any sexual experience.

Others have had homosexual experiences but do not consider themselves to be gay, lesbian, or bisexual.

Youths who had identified as both gay/lesbian and bisexual prior to baseline were approximately three times more likely to identify as gay/lesbian than as bisexual at subsequent assessments.

Of youths who had identified only as bisexual at earlier assessments, 60 to 70 percent continued to thus identify, while approximately 30 to 40 percent assumed a gay/lesbian identity over time. suggested that "although there were youths who consistently self-identified as bisexual throughout the study, for other youths, a bisexual identity served as a transitional identity to a subsequent gay/lesbian identity." By contrast, a longitudinal study by Lisa M.

Diamond, which followed women identifying as lesbian, bisexual, or unlabeled, found that "more women adopted bisexual/unlabeled identities than relinquished these identities," over a ten-year period.

The study also found that "bisexual/unlabeled women had stable overall distributions of same-sex/other-sex attractions." Diamond has also studied male bisexuality, noting that survey research found "almost as many men transitioned at some point from a gay identity to a bisexual, queer or unlabeled one, as did from a bisexual identity to a gay identity." In the 1940s, zoologist Alfred Kinsey created a scale to measure the continuum of sexual orientation from heterosexuality to homosexuality.

heteroflexible, homoflexible, men who have sex with men and women who have sex with women may also be used to describe sexual identity or identify sexual behavior.

Some sources state that bisexuality encompasses romantic or sexual attraction to all gender identities or that it is romantic or sexual attraction to a person irrespective of that person's biological sex or gender, equating it to or rendering it interchangeable with pansexuality.

Bisexual activist Robyn Ochs defines bisexuality as "the potential to be attracted—romantically and/or sexually—to people of more than one sex and/or gender, not necessarily at the same time, not necessarily in the same way, and not necessarily to the same degree." ..development of a lesbian, gay, or bisexual (LGB) sexual identity is a complex and often difficult process.